Safety Tips for Watching a Solar Eclipse
As you know, on August 21, 2017, North America will witness the first solar eclipse to cross the entire continental US in 99 years. The moon will pass between the sun and the Earth casting a shadow over the sun. Depending on your location, you will see either a total or partial eclipse.
The total eclipse will reach the West Coast of the United States – between the Oregon cities of Newport and Lincoln City – at 10:16 a.m. PT (1:16 ET) and last approximately two minutes and 40 seconds. The eclipse will end at 2:49 p.m. ET as the moon’s shadow moves off the Atlantic coast. That means it will take one hour and 33 minutes for the shadow of the moon to cross the country. The path of the totality, in which the moon totally blocks out the sun’s rays, is only about 70 miles wide. Those not in that 70-mile-wide strip across America will still see between a 20 percent to a 99 percent coverage of the sun by the moon.
Watching a solar eclipse safely – regardless of your location- requires some precautions. All over the country, people will be looking up at the sun as the moon approaches, but even though the moon will entirely block the sun only within the narrow path of totality, it is still unsafe to stare directly at the sun at any point during this event. As a footnote, it is always unsafe to stare directly at the sun even when there is not an eclipse going on because the sun puts out more power than our eye is designed to handle. You can damage your retina by looking directly at the sun at any time.
But in a total eclipse situation, the danger is even more pronounced. Think about it – the moon blocks out the sun so it is dark out. In response, your pupils dilate to let in more light. Then suddenly, the sun reappears and floods your eye with intense sunlight. Your pupils can’t constrict fast enough to protect your eyes – that’s the problem. The sun can damage your eyes in an eclipse before you can look away.
NASA’s “Do’s and Don’ts”
According to NASA, there are some clear “do’s and don’ts” necessary to protect your eyes during the upcoming eclipse. Watching a solar eclipse safely includes the following guidelines:
- The only safe way to look directly at the uneclipsed or partially eclipsed sun is through special-purpose solar filters, such as “eclipse glasses” or hand-held solar viewers. Homemade filters or ordinary sunglasses, even very dark ones, are not safe for looking at the sun; they transmit thousands of times too much sunlight.
- Don’t look at the sun and then put on your glasses. Stand still and cover your eyes with your eclipse glasses or solar viewer first – before looking up at the bright sun. And the same applies after looking at the sun – turn away and remove your glasses when your gaze is someplace else.
- A camera or telescope or binoculars do not provide protection. Do not look at the uneclipsed or partially eclipsed sun through an optical device.
- If you are within the path of totality (https://go.nasa.gov/2pC0lhe(link is external)), remove your solar filter only when the moon completely covers the sun’s bright face and it suddenly gets quite dark. Experience totality, then, as soon as the bright sun begins to reappear, replace your solar viewer to look at the remaining partial phases.
- If you normally wear eyeglasses, keep them on. Put your eclipse glasses on over them, or hold your handheld viewer in front of them.
Making a Pinhole Viewer
There are also instructions for what to do if you don’t have elcipse glasses. You can make a pinhole viewer, which will project a shadow of the eclipse on a piece of paper or cardboard. This short video from the Denver post shows you all you need to know.
So, be safe while viewing tomorrow’s eclipse. It promises to be quite a show!